1. Field of Invention
The invention relates to a map data processing method for handling map data stored on a portable readable/writable storage medium, such as a memory card, a map data processing device, the storage medium that can be used therewith, and an on-board map data processing device.
2. Description of Related Art
A system has been known in which the latest map data is stored for a fee on a storage medium (e.g., smart media), called a memory card, from a map data vending machine (hereinafter referred to as “kiosk terminal”) located at a gas station or convenience store or the like. This storage medium is then used with an on-board navigation system or the like, and the map data stored on the storage medium is used for route guidance. An example of this kind of system is disclosed in Japanese Patent Laid-Open Publication No. 2000-146619. According to this system, the use of the latest map data for route guidance enables accurate route guidance to be provided.
According to this system, however, the map data stored on the storage medium can be copied to another storage medium of the same type, and the copied map data can then be used by the navigation system. That is, with this system, it is possible to illegally copy the map data, which would adversely affect the sales of the map data. To counter this, it is conceivable to store the map data on the storage medium after it has been encrypted by the kiosk terminal. The encrypted map data could then be used after it has been decrypted by the navigation system. As a result, illegal copying of the map data can be minimized.
When all of the map data is encrypted, however, it takes time to decrypt it. This method is therefore unsuitable for devices that require rapid data processing, such as navigation systems.